Iran Prepares Improved Centrifuges

Crail, Peter, Arms Control Today

Iran intends to begin its first full-scale testing of its second-generation centrifuge models, according to a Feb. 25 International Atomic Energy Agency (IAEA) report, a move that could allow Tehran to increase the rate at which it enriches uranium.

Even after the testing process, however, Iran would not be able to raise the rate significantly unless it were able to mass produce and operate new machines on a large scale. Current and former U.S. and IAEA officials said they doubted Iran maintained the capabilities to do that.

"Our understanding is that these advanced centrifuges are not yet ready for mass production," Robert Einhorn, the Department of State's special adviser for arms control and nonproliferation, said during a March 9 Arms Control Association briefing. "The Iranians don't yet have sufficient confidence" in the new centrifuges to mass produce and operate them, he said.

Gas centrifuges spin at high speeds to increase the concentration of the fissile isotope uranium-235 from the levels found in natural uranium, a process called enrichment. Low-enriched uranium (LEU) commonly is used to fuel nuclear reactors while highly enriched uranium (HEU) can be used in the core of a nuclear weapon.

The IAEA report said that Iran informed the agency in January of its intention to install two 164-machine cascades of its newly developed centrifuges, called the IR-2m and the IR-4, at its pilot enrichment plant for testing. To date, Iran has tested these improved models only in cascades of up to 20 machines.

The cascades at Iran's commercialscale Natanz plant, where it produces its enriched uranium, operate 164 linked machines using an older, crash-prone centrifuge model called the P-I.

An eventual move to make use of the new centrifuge models would likely increase Iran's uranium-enrichment capacity. "The increase from 20- to 164-machine cascades for the second-generation centrifuges heightens concern that Iran may be on the edge of a breakthrough that would sharply reduce the timeline for HEU production," Mark Fitzpatrick, former deputy assistant secretary of state for nonproliferation, said in a March 21 e-mail.

Although the performance of Iran's newer centrifuge models is unclear, former IAEA safeguards chief Olli Heinonen indicated in a March 2 presentation that the IR-2m has about three times the potential capacity of the P-I.

Tehran obtained the P-I centrifuge, as well as the more advanced P-2 model, from the nuclear smuggling network run by Pakistani nuclear official Abdul Qadeer Khan, who stole the designs from Europe. Both the IR-2m and IR-4 are believed to be derived from the P-2 machine. Iran developed other models based on the P-2, but has since abandoned them.

Iran's decision to continue developing two different models of secondgeneration centrifuges might point to continued difficulties in their development and deployment. Fitzpatrick said that running the new designs in parallel "suggests that they have not yet ironed out all the bugs in either model."

Heinonen said in a March 21 interview that Iran also may have decided to pursue both designs because of material constraints. He said he would not be surprised if Iran were to install both sets of machines for regular operations, expanding them as access to resources allowed.

Unlike the SR-2m, the IR-4 uses a key component called a bellows, made of carbon fiber, to connect multiple centrifuge rotors. Iranian technicians initially determined that they were unable to manufacture this sensitive part, opting instead for single-rotor machines such as the IR2m. Iran appears to have overcome its initial difficulties in manufacturing bellows, but may still face constraints building them in sufficient numbers.

Last April, Iran unveiled what it called a third-generation centrifuge capable of enriching uranium five times faster than the P-I. Although Iranian officials said at the time that they would begin testing the machines within several months and might need a year to install a cascade, Iran has not conducted any work on this new model at its declared nuclear facilities. …

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